1. Field of the Invention
The present invention relates to a test handler, and more particularly to a tray transfer apparatus which is capable of transferring a user tray.
2. Description of the Related Art
Recently, semiconductor devices (which are hereinafter called ‘devices’) have been used in various environments. It is critical for the device to be able to perform even under adverse conditions. Therefore, before the devices can be put on the market, it must undergo tests to determine how they perform under adverse conditions. A test handler according to the present invention serves to determine whether the produced devices perform successfully or unsuccessfully when subject to particular conditions, before they are put on the market. The procedure referred to above is a method for testing these devices.
The technologies related to the test handler are disclosed in: Korean Utility Model Publication No. 20-1998-062568 entitled TRAY CATCHER OF HANDLER SYSTEM FOR TESTING SEMICONDUCTOR DEVICE; Korean Utility Model Publication No. 20-1998-062567 entitled TRANSFER APPARATUS OF HANDLER SYSTEM; Korean Patent No. 10-2003-0062702 entitled TRAY TRANSFER APPARATUS OF TEST HANDER FOR SEMICONDUCTOR DEVICE; Korean Patent Publication No. 10-2004-0043925 entitled TRAY TRANSFER APPARATUS; Korean Patent No. 10-2002-25 0031461 entitled TRAY TRANSFER APPARATUS FOR HANDLER; and Korean Patent No. 10-2003-0029266 entitled TEST HANDLER. These publication materials disclose structures of test handler in detail. As disclosed in the publication materials, the test handler includes a tray transfer apparatus for transferring a user tray under a transfer standby state to a transfer position as 5 the tray transfer apparatus grips one of a plurality of user trays loaded in stackers which are installed under the loading plates and unloading plates. It then performs a movement to transfer the gripped user tray to the loading plate and the unloading plate or the tray transfer apparatus grips a user tray, which is located at the loading plate and unloading plate, to perform a movement to stack the gripped user tray on the stacker. The present invention relates to technical characteristics of the tray transfer apparatus. Here, the phrase “transfer standby state” means states where a user tray must be transferred, such as, a state where a corresponding user tray is loaded on the stacker when the user tray includes a target device to be tested, or a state where a corresponding user tray is located at the loading or unloading plate immediately after finishing a Loading or unloading operation. Also, the phrase “transfer positions” means positions to which a user tray under the transfer standby state must be transferred, such as, a position of a loading plate for a user tray in which a target device to be tested is included, where the user tray is loaded on the stacker, or a position of an unloading plate for an empty user tray which finishes a loading operation in the loading plate. Such concepts will be identically applied to the following description.
FIG. 1 is a block diagram illustrating a tray transfer apparatus 100 of a conventional test handler. Referring to FIG. 1, the conventional tray transfer apparatus 100 includes a transfer 101 having a pair of grippers 11a and 11b which selectively grip or un-grip a user tray and a pair of vertical movement units 12a and 12b which vertically move the pair of grippers 11a and 11b, respectively, a horizontal movement unit 102 which horizontally moves the transfer 101, and a controller 103 which controls the pair of vertical movement units 12a and 12b and the vertical movement unit 102. The conventional tray transfer apparatus 100 was disclosed, in detail, in FIG. 2 and the description related thereto in Korean Utility Model Publication No. 20-1998-062567 (which is hereinafter referred to as the “cited reference”). In the cited reference, the tray transfer apparatus was expressed as a transfer apparatus and a pair of grippers was expressed as a transfer head.
However, since the pair of grippers 11a and 11b are independently moved in a vertical direction and are always moved together in a horizontal direction, when events (a state where a user tray is in a transfer standby state as the user tray on a loading plate or an unloading plate completely performs a loading or unloading, whose meaning will be identically applied to the following descriptions) simultaneously occur on the loading plate and the unloading plate, a user tray under a transfer standby state on one of them must keep its state. Therefore, the conventional tray transfer apparatus 100 is disadvantageous in that its process speed decreases.
Also, since the conventional tray transfer apparatus 100 is implemented in a single transfer 101 together with other elements, a pair of grippers 11a and 11b perform all of transferring operations while moving together in a horizontal direction. In addition, because it is difficult to know whether an event occurs at a loading plate or an unloading plate, the conventional tray transfer apparatus cannot perform gripping, moving and waiting operations without preceding procedures. Namely, the apparatus cannot perform moving and waiting operations without preceding procedures while it grips a user tray under a transfer standby state. Therefore, the conventional tray transfer apparatus is disadvantageous in that the process speed decreases.
In addition, since all of the pairs of grippers 11a and 11b must be moved horizontally from the loading plate section to the unloading plate section, the horizontal movement distance is relatively elongated. Therefore, the conventional tray transfer apparatus is disadvantageous in that the process speed decreases.
The above-mentioned problems are more obvious in this field because future technologies for test handlers will be developed so that the test handlers can process devices with larger capacities.